{289} In self-defence there should of course be a proportion between the injury which the aggressor intended to inflict and the injury inflicted on him by the person attacked. The most widely-recognised ground on which life is allowed to be taken in self-defence is danger of death. But it is not the exclusive ground. Among the Wakamba "a thief entering a village at night can be killed"; though, if he is, the incident generally gives rise to a blood-feud between his family and the family of the slayer.[39] In Uganda "there is no penalty for killing a thief who enters an enclosure at night";[40] and among various peoples at higher stages of culture we likewise find the provision that a nocturnal thief or house-breaker may be killed with impunity, though a diurnal thief may not.[41] This law, however, seems to have been due not so much to the fact that by night the proprietor had less chance of recovering his property, as to the greater danger to which he was personally exposed.[42] The Roman Law of the Twelve Tables allows the diurnal thief also to be killed, in case he defends himself with a weapon;[43] and, as regards the nocturnal thief, Ulpian expressly says that the owner of the property is justified in killing him only if he cannot spare the life of the thief without peril to himself.[44] The same rule was laid down by Bracton[45] and by Grotius. The latter observes, "No one ought to be slain directly for the sake of mere things, which would be done if I were to kill an unarmed flying thief with a missile, and so recover my goods: but if I am myself in danger of life, then I may repel the danger even with danger to the life of another; nor does this cease to hold, however I have come into that danger, whether by trying to retain my property, or to {290} recover it, or to capture the thief; for in all these cases I am acting lawfully according to my right."[46] [Footnote 39: Decle, _Three Years in Savage Africa_, p. 488.] [Footnote 40: Ashe, _Two Kings of Uganda_, p. 294.] [Footnote 41: _Ta Tsing Leu Lee_, sec. cclxxvii. p. 297 (Chinese). _Exodus_, xxii. 2 _sq._ _Lex Duodecim Tabularum_, viii. 11 _sq._ Plato, _Leges_, ix. 874. _Lex Baiuwariorum_, ix. (viii.) 5. Du Boys, _Histoire du droit criminel de l'Espagne_, p. 288 (Spanish Partidas).] [Footnote 42: _Cf._ Gregory IX. _Decretales_, v. 12. 3; _Mishna_, fol. 72, quoted by Rabbinowicz, _Législation criminelle du Talmud_, p. 122.] [Footnote 43: _Lex Duodecim Tabularum_, viii. 12. Cicero, _Pro Milone_, 3 (9).] [Footnote 44: _Digesta_, xlviii. 8. 9.] [Footnote 45: Bracton, _op. cit._ fol. 144 b, vol. ii. 464 _sq._] [Footnote 46: Grotius, _De jure belli et pacis_, ii. 1. 12. 1.]